#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "crc32.h"
#ifndef BUILD_WITH_VCC
#include <unistd.h>
#endif

#ifndef O_BINARY
#define O_BINARY 0
#endif

int debug;

/* crc32tab[]:
 *	Used for calculating a 32-bit CRC.
 */
static unsigned long crc32tab[] = {
	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
	0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 
	0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
	0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 
	0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
	0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 
	0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
	0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 
	0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
	0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 
	0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
	0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 
	0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
	0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 
	0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
	0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 
	0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
	0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 
	0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
	0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 
	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
	0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 
	0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
	0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 
	0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
	0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 
	0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
	0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 
	0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
	0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 
	0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
	0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 
	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
	0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 
	0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
	0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 
	0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
	0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 
	0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
	0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 
	0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
	0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 
	0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
};

/* crc32:
 * Assumes the entire buffer across which the CRC is to be run is in
 * the incoming buffer.
 */
unsigned long
crc32(unsigned char *buffer,unsigned long nbytes)
{
	int	temp;
	unsigned long crc_rslt;

	crc_rslt = 0xffffffff;
	while(nbytes) {
		temp = (crc_rslt ^ *buffer++) & 0x000000FFL;
		crc_rslt = ((crc_rslt >> 8) & 0x00FFFFFFL) ^ crc32tab[temp];
		nbytes--;
	}
	return(~crc_rslt);
}

/* partial_crc32:
 * Assumes only a portion of the buffer across which the CRC is to be run
 * is in the incoming buffer.  It is also fed the running crc value.
 */
unsigned long
partial_crc32(unsigned long crcval, unsigned char *buffer,unsigned long nbytes)
{
	int	temp;

	crcval = ~crcval;
	while(nbytes) {
		temp = (crcval ^ *buffer++) & 0x000000FFL;
		crcval = ((crcval >> 8) & 0x00FFFFFFL) ^ crc32tab[temp];
		nbytes--;
	}
	return(~crcval);
}

/* ofcrc32:
 * Run the same CRC on a file as is run in the "mt -C" command
 * in the monitor...
 * This is the 'old' version.  It works as long as the file is small.
 * If the file is big, then malloc will fail; hence, the need for a
 * new version that will read chunks instead of doing one big malloc.
 */
int
ofcrc32(char *filename, unsigned long *crc, int verbose)
{
	char *buf;
	int	ifd, opt;
	unsigned long tmpcrc;
	struct	stat	mstat;

	/* Open input file: */
	ifd = open(filename,O_RDONLY | O_BINARY);
	if (ifd == -1) {
		perror(filename);
		return(-1);
	}
	fstat(ifd,&mstat);

	if ((buf = malloc(mstat.st_size)) == 0) {
		close(ifd);
		perror("malloc");
		return(-1);
	}
	
	if (read(ifd,buf,mstat.st_size) != mstat.st_size) {
		close(ifd);
		perror("read");
		return(-1);
	}
	close(ifd);

	tmpcrc = crc32(buf,mstat.st_size);
	if (verbose)
		printf("CRC of file %s: 0x%x\n",filename,tmpcrc);

	if (crc)
		*crc = tmpcrc;

	return(0);
}

/* fcrc32():
 * Same as ofcrc32 except that it breaks the file into chunks of
 * 64K so that there is no big malloc done if the file is large.
 */
int
fcrc32(char *filename, unsigned long *crc, int verbose)
{
	char	buf[0x10000];
	unsigned long tmpcrc;
	struct	stat	mstat;
	int		ifd, opt, size;

	/* Open input file: */
	ifd = open(filename,O_RDONLY | O_BINARY);
	if (ifd == -1) {
		perror(filename);
		return(-1);
	}
	fstat(ifd,&mstat);

	tmpcrc = 0;
	size = mstat.st_size;
	while(size > 0) {
		if (size > sizeof(buf)) {
			if (read(ifd,buf,sizeof(buf)) != sizeof(buf)) {
				close(ifd);
				perror("read1");
				return(-1);
			}
			tmpcrc = partial_crc32(tmpcrc,buf,sizeof(buf));
			size -= sizeof(buf);
		}
		else {
			if (read(ifd,buf,size) != size) {
				close(ifd);
				perror("read1");
				return(-1);
			}
			tmpcrc = partial_crc32(tmpcrc,buf,size);
			size = 0;
		}
	}
	close(ifd);

	if (verbose)
		printf("CRC of file %s: 0x%x\n",filename,tmpcrc);

	if (crc)
		*crc = tmpcrc;

	return(0);
}
